JP 2002-89594 A, issued in 2002 by the Japan Patent Office, discloses an automated manual transmission (hereinafter called AMT) as a transmission for a hybrid vehicle that uses an engine and a motor as drive sources. Gear shift operations of a manual transmission having a high transmission efficiency are automated in the AMT.
This conventional transmission comprises a first rotation shaft and a second rotation shaft that are disposed in parallel with a crankshaft of an engine, and a third rotation shaft to which rotation of the first rotation shaft or the second rotation shaft is selectively output. A driving force from the engine is transmitted to the first rotation shaft and the second rotation shaft through a common gear. The motor used as the drive source is connected to the second rotation shaft. A plurality of gears are provided to the first rotation shaft, the second rotation shaft, and the third rotation shaft. The transmission function is realized by meshing of the gears on the first rotation shaft and the gears on the second rotation shaft, as well as meshing of the gears on the second rotation shaft and the gears on the third rotation shaft. The first rotation shaft is provided with first, third, and fifth speed gear positions, and the second rotation shaft is provided with a second, fourth, and sixth speed gear positions.
The first rotation shaft and the second rotation shaft are each provided with a clutch that transmits or cuts off the driving force from the engine. The clutch on the first rotation shaft engages, and the clutch on the second transmission shaft is placed in a free state, when the first rotation shaft transmits the driving force. The clutch on the first rotation shaft is placed in a free state, and the clutch on the second rotation shaft is engaged, when the second rotation shaft transmits the driving force.
When shifting gears from the first speed gear to the second speed gear, the clutch on the first rotation shaft is switched over to a free state, and the clutch on the second rotation shaft is switched over to an engaged state. Gear shifts can thus be made without cutting off transmission of the driving force to the third rotation shaft.